Oceanography Department, Faculty of Science, Alexandria University, Moharem Bek, Alexandria, 21511, Egypt.
Probiotics Antimicrob Proteins. 2020 Jun;12(2):365-374. doi: 10.1007/s12602-019-09575-0.
A 50-day feeding trial was conducted to evaluate the effects of dietary supplementation of a novel marine psychrotrophic bacterium, Psychrobacter maritimus S, on growth performance and immune responses of Nile tilapia (Oreochromis niloticus) fingerlings. Triplicate groups of Nile tilapia (10 fish each) were fed for 50 days with three different diets: T (without probiotic, negative control), T (supplemented with 3.3 × 10 CFU gP. maritimus S), and T (supplemented with 6.6 × 10 CFU gP. maritimus S). The test diets were fed to fish at a daily rate of 3% of their live weights, three times per day. On the 50th day, fish were weighed and blood samples were collected to determine the main nonspecific humoral and cellular immune responses and digestive enzymes (protease, amylase, and lipase). Fish performance (weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio, and protein productive value) was also calculated. Growth rates and digestive enzyme activity were significantly increased (P < 0.05) with increasing dietary P. maritimus S up to 0.5%, and leveled off with further increase in bacterial concentrations. Phagocytic activity, lysozyme activity, alternative complement hemolysis, and hematological parameters were also significantly increased (P < 0.05) with increasing P. maritimus S concentration to 0.5%, followed by a slight decrease (P > 0.05) at 1% level. The expression of interleukin-4 and interleukin-12 genes was significantly upregulated, while heat shock protein gene was downregulated, with dietary supplementation of P. maritimus S up to 0.5% level. These results suggest that 0.5% of dietary Psychrobacter maritimus S supplementation could be considered as a novel probiont for optimum growth performance and immune response of Nile tilapia fingerlings.
一项为期 50 天的饲养试验旨在评估新型海洋嗜冷菌 Psychrobacter maritimus S 对尼罗罗非鱼（Oreochromis niloticus）幼鱼生长性能和免疫反应的影响。将 3 组（每组 10 条鱼）尼罗罗非鱼分别用 3 种不同的饲料喂养 50 天：T（无益生菌，阴性对照）、T（添加 3.3×10^9 CFU gP. maritimus S）和 T（添加 6.6×10^9 CFU gP. maritimus S）。试验饲料按鱼体重的 3%，每日投喂 3 次。第 50 天，称鱼重并采集血样，以测定主要非特异性体液和细胞免疫反应以及消化酶（蛋白酶、淀粉酶和脂肪酶）。还计算了鱼的生长性能（增重、特定生长率、饲料转化率、蛋白质效率比和蛋白质生产价值）。随着饲料中 P. maritimus S 的浓度增加到 0.5%，生长率和消化酶活性显著提高（P<0.05），进一步增加细菌浓度则达到稳定水平。吞噬活性、溶菌酶活性、替代补体溶血和血液学参数也随着 P. maritimus S 浓度增加到 0.5%而显著提高（P<0.05），随后在 1%水平略有下降（P>0.05）。随着饲料中 P. maritimus S 的添加量增加到 0.5%，白细胞介素-4 和白细胞介素-12 基因的表达显著上调，而热休克蛋白基因的表达则下调。这些结果表明，饲料中添加 0.5%的 Psychrobacter maritimus S 可被视为尼罗罗非鱼幼鱼最佳生长性能和免疫反应的新型益生菌。
